Conventionally, a printer designed to perform a printing task by transferring an ink that is curable by irradiation of ultraviolet (UV) light to a target object such as paper is known. Such a printer is equipped with a UV light illuminating apparatus to cure the ink on the target object. In keeping with the demand for lower power consumption or longer service life, a UV light illuminating apparatus configured to use a Light Emitting Diode (LED) as an alternative to a traditional discharge lamp for a light source is proposed (for example, Patent Literature 1).
The UV light illuminating apparatus (LED unit) disclosed in Patent Literature 1 is equipped with a plurality of base blocks where a plurality of LED modules (LED chips) is arranged at a regular interval in lengthwise direction (first direction) to emit light of a line shape. Each base block is inclined at a predetermined angle to focus light of a line shape emitted from each base block into a line at a predetermined position on a target object, and is arranged and placed at a predetermined interval in widthwise direction (second direction).